The present invention relates to hydroponic systems, and especially to a hydroponic system having a floating hydroponic tray for the growth of hydroponic plants and to a specially designed pool for the floating trays.
In the past, a wide variety of hydroponic devices have been provided for growing plants in a liquid nutrient. Typical hydroponic devices have supporting materials, such as rocks, to support the plant roots. Most prior art devices, however, are directed towards small containers for use in the home by individuals for growing their own plants. The present invention, on the other hand, is for commercial hydroponic farming which can be done on otherwise wasted swamp land or in specially constructed pools, in accordance with the present invention, and which pools can be utilized for harvesting shrimp or fish or other marine organisms in the pools below the floating hydroponic trays. Another advantage of the present invention is that floating trays are made of a lightweight concrete, which is fairly permanent and inexpensive to manufacture. However, since concrete is made with lime, the concrete will not totally prevent the seepage of water therethrough. A special treatment and coating is used on the concrete trays to prevent a shift in the pH in the hydroponic tray, which could damage plants which are frequently very sensitive to soil pH.
The present invention is a joint invention on U.S. Pat. No. 4,011,355 for a method emulsion coating for lightweight aggregate is for a method which uses hydrated alumina and dehydrated lime coating of beads, but this coating composition was well known long before this patent. In my prior U.S. Pat. No. 4,241,107 for a roof coating process, a method of applying lightweight cement to roofs is shown.